Prezi has an autosave function to commit your presentation to memory. You can also save it yourself by clicking on save in present/file/save. This circle tells you when your work was autosaved for the last time. You can elegantly quit by clicking on save & close, which saves your work and drops you off in your profile view.

We also have an undo function. You can undo your work as far as you don't close the browser window. Undo and Redo are accessible under place. Mind that if you save the presentation, you cannot undo any wrong you have done before the save. Up and Down moves the selected object over or under another overlapping object (e.g. if you have two pictures, you can put one under the other).